It is known in the prior art to extract waste heat from an internal combustion engine by circulating a liquid through a closed-loop system having channels within the engine's block and radiators external to the engine's block. Such systems are effective, but such systems add weight and complexity to the engine, and also make the engine larger and more difficult to maintain.
It is also known in the art to cover external parts of an engine, such as an exposed surface of cylinder and cylinder head for example, with heat-radiating fins that provide a large surface area exposed to cooling air external to the engine. Such systems are effective in some applications, but require open space to allow for air flow around the engine, thereby requiring an engine compartment significantly larger than the engine, and/or ductwork direct air flow to and from the engine. In addition, dissipating heat via the external surface of an engine risks exposing the engine's user, such as a motorcycle rider for example, to the dangerously hot fins.